Perforating gun brake

ABSTRACT

A perforating gun brake includes a first body having an axis. Several gripping feet are provided each having a pivot end and a remote end. The pivot end is pivotally mounted to the first body. The gripping feet are movable between a stored position substantially parallel to the axis of the first body and an engaging position extending outwardly at an angle in relation to the first body. A second body is coupled to and axially movable relative to the first body. A wedge member is carried by the second body. The wedge member exerts a force upon the remote end of the gripping feet upon movement of the second body to force the gripping feet outwardly into the engaging position.

FIELD OF THE INVENTION

[0001] The present invention relates to a perforating gun brake.

BACKGROUND OF THE INVENTION

[0002] Perforating guns are used to create perforations in a well casing so that a fluid can flow from an underground formation into the interior of the well casing and thence be withdrawn from a well. There are several types of perforating gun that can be lowered into a well on a wireline, detonated electronically via the wireline, and then withdrawn from the well.

[0003] When the perforating gun is detonated, gases in the annulus caused by the detonation tend to propel the perforating gun up the well casing. In addition, upon a well casing being perforated, fluids (both liquids and gas) from the formation rapidly enter the well casing through the perforations. As the fluids enter the well casing they also tend to move the perforating gun up the well bore. To counter this action, a perforating gun brake can be used.

[0004] Mohaupt in U.S. Pat. No. 4,852,647 describes a perforating gun brake including gripping feet that are maintained in engagement with the well casing by means of springs. When the charge in the perforating gun is detonated, shear pins retaining the springs in a compressed position are sheared, the springs are then freed to expand, and the gripping feet are thereby deployed. The gripping feet are unable to retract to the disengaged position against the force of the springs in the expanded position, and so remain in engagement with the well casing as the perforating gun brake is withdrawn from the well.

[0005] Blimke in U.S. Pat. No. 5,700,968 that issued in 1997 describes a perforating gun brake that also uses gripping feet to engage a well casing. As with the Mohaupt reference, when the charge in the perforating gun is detonated, shear pins retaining springs in a compressed position are sheared. The springs then expand to deploy gripping feet. Detonation of a second explosive charge within the perforating gun brake is required to release a hydraulic retaining collar. This releases tension on the spring that deploys the gripping feet and permits the gripping feet to move back into a retracted position as the perforating gun brake is removed from the well casing. It will be understood that the perforating gun brakes described by Mohaupt and Blimkie both must be refurbished after each use.

SUMMARY OF THE INVENTION

[0006] What is required is a perforating gun brake that is simple to operate and that does not require replacement or repair of parts after each use.

[0007] According to the present invention there is provided a perforating gun brake which includes a first body having an axis. Several gripping feet are provided each having a pivot end and a remote end. The pivot end is pivotally mounted to the first body. The gripping feet are movable between a stored position substantially parallel to the axis of the first body and an engaging position extending outwardly at an angle in relation to the first body. A second body is coupled to and axially movable relative to the first body. A wedge member is carried by the second body. The wedge member exerts a force upon the remote end of the gripping feet upon movement of the second body to force the gripping feet outwardly into the engaging position.

[0008] With the perforating gun brake, as described above, the force of detonation drives the second body toward the first body. As the second body moves toward the first body, the wedge member forces the gripping feet into the engaging position. Once the force of the detonation has subsided, the weight of the perforating gun pulls the second body away from the first body. This disengages the wedge member to permit the gripping feet to return to the stored position in preparation for withdrawing the perforating gun brake from the well casing.

[0009] Although beneficial results may be obtained through the use of the perforating gun brake, as described above, even more beneficial results may be obtained when a spring is positioned to exert a biasing force upon the second body to bias the second body away from the first body. The additional force of the spring assists the gripping feet to release.

[0010] There are various configurations that can accomplish the above described objectives. Beneficial results have been obtained by providing the first body with an interior bore and having the second body telescopically received in the interior bore of the first body.

[0011] There are, similarly, various configurations of wedge member that can be used. Beneficial results have been obtained through the use of a conical wedge member.

[0012] Although beneficial results may be obtained through the use of the perforating gun brake, as described above, even more beneficial results may be obtained when an expandable retainer is positioned about the gripping feet to exert a biasing force upon the gripping feet to bias the gripping feet into the stored position. The force of the expandable retainer prevents unplanned outward movement of the gripping feet. The use of the expandable retainer is especially beneficial when the perforating gun is to be used in a well that is not vertical, as the force of gravity acting on a freely pivoting gripping foot may cause it to fall away from the perforating gun brake toward the well casing as the perforating gun is lowered in position.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings, wherein:

[0014]FIG. 1 is a side elevation view, in section, of a perforating gun brake constructed in accordance with the teachings of the present invention, prior to detonation;

[0015]FIG. 2 is a side elevation view, in section of the perforating gun brake illustrated in FIG. 1, upon detonation; and

[0016]FIG. 3 is a side elevation view, in section of the perforating gun brake illustrated in FIG. 1, after the forces associated with detonation have subsided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] The preferred embodiment, a perforating gun brake generally identified by reference numeral 10, will now be described with reference to FIGS. 1 through 3.

[0018] Referring to FIG. 1, perforating gun brake 10 includes a first body 12 and a second body 14. First body 12 has an axis 15, an exterior surface 16, a first end 18, a second end 20, and an interior bore 22 accessible from second end 20 of first body 12. A wireline attachment 24 is at first end 18 of first body 12 whereby first body 12 is suspended from a wireline 26. Each of several gripping feet 28 has a pivot end 30 and a remote end 32. The several gripping feet 28 are pivotally mounted at pivot end 30 to second end 20 of first body 12. Referring to FIGS. 1 and 2, each of the gripping feet 28 is movable between a stored position substantially parallel to first body 12, illustrated in FIG. 1, and an engaging position extending outwardly at an angle in relation to axis 15 of first body 12, illustrated in FIG. 2. Referring to FIG. 1, an expandable retainer 33 normally retains gripping feet 28 in the stored position parallel to first body 12. Expandable retainer 33 can be in the form of a rubber strap.

[0019] Second body 14 has a first end 34, a second end 36, and a cylindrical central portion 37. First end 34 and central portion 37 of second body 14 are telescopically received in interior bore 22 at second end 18 of first body 12. Gripping feet 28 are retained in position against a surface 39 of central portion 37 of second body 14 by expandable retainer 33 when in the stored position. Second body 14 is telescopically movable relative to first body 12 between an extended position, illustrated in FIG. 1, and a compressed position, illustrated in FIG. 2. A perforating gun attachment 38 is at second end 36 of second body 14, whereby a perforating gun 40 is attached to second body 14. Electrical wiring extends through a conduit 41 from wireline attachment 24 at first end 18 of first body 12 to perforating gun attachment 38 at second end 36 of second body 14, whereby an electrical signal to trigger detonation is transmitted via wireline 26 secured to wireline attachment 24 to perforating gun 40 secured to perforating gun attachment 38.

[0020] A conical wedge member 42 is carried by central portion 37 at the end of central portion 37 toward second end 36 of second body 14. Wedge member 42 engages remote end 32 of gripping feet 28. Referring to FIG. 2, when perforating gun 40 detonates, explosive charges 50 explode radially, as shown by arrows 52, causing perforations 54 in a well casing 56. Detonation causes movement urging perforating gun brake 10 up the well. This force is first exerted upon and causes movement of second body 14 toward first end 18 of first body 12. Upon movement of second body 14 as result of detonation of perforating gun 40, wedge member 42 forces gripping feet 28 outwardly, against a retaining force from expandable retainer 33, from the stored position parallel to axis 15 of first body 12 and into the engaging position. An upward force on perforating gun 40 is caused by gases in the annulus caused by the detonation, shown by open arrows 58, but the force is prevented from forcing perforating gun 40 a large distance up well casing 56 by the gripping action of remote ends 32 of gripping feet 28 on well casing 56.

[0021] Referring to FIGS. 1 and 3, a spring 44 disposed within interior bore 22 of first body 12 exerts a biasing force upon first end 34 of second body 14 to bias second body 14 away from first end 18 of first body 12. Referring to FIG. 3, when the forces unleashed by detonation of perforating gun 40 subside, second body 14 is biased away from first end 18 of first body 12, moving wedge member 42 from away from gripping feet 28, illustrated in FIG. 2, and permitting gripping feet 28 to be disengaged from well casing 56 and return to the stored position, illustrated in FIG. 3. Expandable retainer 33 exerts a force axially inward upon gripping feet 28, urging gripping feet 28 back to the stored position.

[0022] It will be apparent to one skilled in the art that modifications maybe made to the illustrated embodiment without departing from the spirit and scope of the invention as hereinafter defined in the claims. 

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. A perforating gun brake, comprising: a first body having an axis; several gripping feet having a pivot end and a remote end, the pivot end being pivotally mounted to the first body, the gripping feet being movable between a stored position substantially parallel to the axis of the first body and an engaging position extending outwardly at an angle in relation to the first body; a second body coupled to and axially movable relative to the first body; and a wedge member carried by the second body, the wedge member exerting a force upon the remote end of the gripping feet upon movement of the second body to force the gripping feet outwardly into the engaging position.
 2. The perforating gun brake as defined in claim 1 , wherein a spring exerts a biasing force upon the second body to bias the second body away from the first body.
 3. The perforating gun brake as defined in claim 1 , wherein the first body has an interior bore, and the second body is telescopically received in the interior bore of the first body.
 4. The perforating gun brake as defined in claim 1 , wherein an expandable retainer holds the gripping feet in the stored position until a counteracting force is exerted by the wedge member.
 5. A perforating gun brake, comprising: a first body having an axis, an exterior surface, a first end, a second end, and an interior bore accessible from the second end of the first body; a wireline attachment at the first end of the first body whereby the first body is suspended from a wireline; several gripping feet having a pivot end and a remote end, the pivot end being pivotally mounted to the second end of the first body, the gripping feet being movable between a stored position substantially parallel to the axis of the first body and an engaging position extending outwardly at an angle in relation to the first body; a second body having a first end and a second end, the first end of the second body being telescopically received in the interior bore at the second end of the first body, such that the second body is telescopically movable relative to the first body; a perforating gun attachment at the second end of the second body, whereby a perforating gun is attached to the second body; and a wedge member carried by the second body, the wedge member engaging the remote end of the gripping feet upon movement of the second body to force the gripping feet outwardly into the engaging position.
 6. The perforating gun brake as defined in claim 5 , wherein a spring disposed within the interior body of the first body exerts a biasing force upon the first end of the second body to bias the second body away from the first body.
 7. The perforating gun brake as defined in claim 5 , wherein electrical wiring extends from the wireline attachment at the first end of the first body to the perforating gun attachment at the second end of the second body, whereby an electrical signal to trigger detonation is transmitted via a wireline secured to the wireline attachment to a perforating gun secure to the perforating gun attachment.
 8. The perforating gun brake as defined in claim 4 , wherein the wedge member is a cone.
 9. The perforating gun brake as defined in claim 5 , wherein an expandable retainer holds the gripping feet in the stored position until a counteracting force is exerted by the wedge member.
 10. A perforating gun brake, comprising: a first body having an axis, an exterior surface, a first end, a second end, and an interior bore accessible from the second end of the first body; a wireline attachment at the first end of the first body whereby the first body is suspended from a wireline; several gripping feet having a pivot end and a remote end, the pivot end being pivotally mounted to the second end of the first body, the gripping feet being movable between a stored position substantially parallel to the axis of the first body and an engaging position extending outwardly at an angle in relation to the first body; a second body having a first end and a second end, the first end of the second body being telescopically received in the interior bore at the second end of the first body, such that the second body is telescopically movable relative to the first body; a perforating gun attachment at the second end of the second body, whereby a perforating gun is attached to the second body; electrical wiring extends from the wireline attachment at the first end of the first body to the perforating gun attachment at the second end of the second body, whereby an electrical signal to trigger detonation is transmitted via a wireline secured to the wireline attachment to a perforating gun secured to the perforating gun attachment, a conical wedge member carried by the second body, the wedge member engaging the remote end of the gripping feet such that upon movement of the second body as a result of detonation of the perforating gun the wedge member forces the gripping feet outwardly into the engaging position; and a spring disposed within the interior body of the first body exerting a biasing force upon the first end of the second body to bias the second body away from the first body, such that when the forces unleashed by detonation of the perforating gun subside the second body is biased away from the first body thereby releasing the wedge member and permitting the gripping feet to return to the stored position.
 11. The perforating gun brake as defined in claim 10 , wherein an expandable retainer holds the gripping feet in the stored position until a counteracting force is exerted by the wedge member. 